GB2044305A

GB2044305A - Producing an Anti-static Carpet Fibre

Info

Publication number: GB2044305A
Application number: GB8007090A
Authority: GB
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1979-03-03
Filing date: 1980-03-03
Publication date: 1980-10-15
Also published as: DE2908376C2; ES489101A0; CH637797GA3; DE2908376A1; CH637797B; IT1143075B; FR2450890B1; GB2044305B; BE881998A; FR2450890A1; ES489099A1; IT8048043A0; ES8301508A1

Abstract

Anti-static carpet fibre is produced by adding a small proportion of electrically conductive fibres to fibres of a synthetic linear polymer which form the pile. Firstly, the pile fibres (5) are produced from a yarn (3) by means of a severing device (1, 2) and the electrically conductive fibres (14) are formed separately by severing a sliver (12) and opened to form individual fibres by means of, for example, an opening roller (10). These conductive fibres are delivered to the flow of pile fibres (5) and mixed therewith prior to collection. <IMAGE>

Description

SPECIFICATION A Method of Producing an Anti-static Carpet Fibre The present invention is a method of producing an anti-static carpet fibre by adding a small amount of electrically conductive fibres to the fibres which form the pile and consist of a synthetic, linear polymer.

A thread material has been used for a long time for the production of carpets, particularly for the production of so-called lay-out products, particularly for the pile i.e. for the fibres forming the surface of the carpet. This fibre material usually consists of a synthetic high-polymeric material, for example nylon 6 or nylon 6.6, because of its high resistance to abrasion and elasticity. These pile fibres have also proved to be effective in respect of stability, resistance to abrasion and colourfastness, etc, however, they have a substantial disadvantage in that they become charged electro-statically when walked upon as a result of their high electrical resistance.

As this fact greatly decreases their usefulness, attempts have been made for a long time to produce a carpet fibre whose electrical resistance is low enough to restrict the resulting electrical charges to a figure which is no longer so high as to be disturbing; the limit is generally stated as being at approximately 2000 volts.

In order to achieve this objective, different courses of action have been taken. For example, continuous, thin, metal wires having a diameter in the range of approximately from 8 to 1 5 Mm, socalled carbon black threads, e.g. threads which consist of a mixture of carbon black and a polymer which is spinnable from a melt, bi-component threads comprising a component containing carbon black and the like, were mixed in as continuous threads with the yarn to be severed so that the staple fibre bundles produced in cutting the yarn contained respectively, a corresponding proportion of electrically conductive fibre portions.

Particularly when using metal wires or carbon black threads, the dye of the admixtures was a considerably disturbing factor especially when light dyes were used for dyeing the carpet fibres.

Attempts were made to counter this disadvantage to some extent in that bicomponent threads were added in the form of core-sheath-threads, in which the electrically conducting core was covered by a sheath having a comparatively high addition of delustring agents, for example titanium dioxide, in order to subdue the influence of the dark core colouring as far as possible. This solution did indeed produce a very favourable effect both in respect of the grounding of static electricity as well as in respect of its visibility; however, the cost of production of such threads was so great that it greatly restricted their commercial utility. In contrast to this, as a substantially simpler and also less expensive measure, the admixture of simple fibres which conduct electricity sufficiently, for example carbon fibres, had to be considered.

Accordingly, a technical object of the present invention is to provide a method of admixing electrically conductive fibres with a carpet fibre material which preferably can be used as the pile for a carpet lay-out product so that the electrostatic charge of 2000 volts at 30% relative humidity, generally applicable as the limiting value for a functional anti-static carpet finish, is not exceeded, wherein at the same time the visibility of the admixed electrically conductive fibres is kept at as low a level as possible.

Surprisingly, it has now been found that it is possible to admix electrically conductive fibres, even carbon fibres, such that their colouring effect and their effect with respect to the grounding of static electricity is no worse than that of the coresheath-fibres previously described. It is obvious that the substantially simpler production opportunity provides such a considerable technical advantage.

According to the present invention there is provided a method of producing an anti-static carpet fibre by adding a small proportion of electrically conductive fibres to fibres comprising a synthetic linear polymer which form the pile, wherein the pile fibres are first produced from a yarn by means of a fibre severing device and, the electrically conductive fibres are formed by severing in a separate working step and are opened to form individual fibres and are mixed in small quantity with the severed pile fibres prior to collection of said severed pile fibres.

The admixed quantity of electrically conducting fibres is preferably approximately from 0.05 to 1%. The fibre length and also the titre are advantageously different for the pile and electrically conductive fibres, such that both the titre and the cut length of the electrically conductive fibres are less than the corresponding values for the pile fibres. Titres of between approximately from 2 and 10 dtex and lengths of approximately from 40 to 80 mm have proved to be particularly effective for the electrically conductive fibre with corresponding values for the pile fibre of approximately from 5 to 20 dtex and lengths of approximately from 120 to 220 mm.In general, values of less than 2, for example 0.5 and greater than 10 dtex to approximately 20 dtex or approximately from 25 mm to 160 mm in length are possible for the electrically conductive fibre and approximately from 2 to 30 dtex with lengths of approximately from 80 to 250 mm being possible for the pile fibre.

Whilst the pile fibre has a basic crimp, usually, for example, a compressed crimp or a toothed wheel crimp or the like, such that the number of bows can amount to approximately from 60 to 220 bows per 100 mm, the electrically conductive fibre can be admixed both as a smooth and as a crimped fibre. However, the admixture of smooth, electrically conductive fibres is only appropriate when they, for example, a carbon fibre, has a very considerable shrinkage which can be approximately in the range of from 8 to 12% boiling shrinkage. This then has the effect that, when dyeing the finished carpet product, the electrically conductive fibres situated in the pile shrink substantially more than the pile fibres and thereby comparatively disappear substantially from the visibility range.

The electrically conductive fibre can also be added as a textured fibre, which then has the advantage that the readiness to open and thereby the possibility of simultaneous distribution in the carpet is improved. Here, the type of texturing has no great significance. Therefor, for example, compression or toothed wheel crimping can be used just as well as texturing using friction-false twist devices.

The preparation and admixture of the electrically conductive fibre is effected according to the invention such that the electrically conductive fibre is presented as a yarn or sliver whereby the sliver weight can advantageously be approximately from 3 to 6 g per metre. It may consist of 100% of electrically conductive fibres as well as of a mixture of, for example, 30 to 50% electrically conductive fibres and 70 to 50% nonconductive polyamide fibres or of another fibre of a comparable titre which are commonly severed.

The fibre or card sliver which contains electrically conductive fibres either to 100% or to at least 30%, preferably exhibits a crimp of approximately from 20 to 80 crimped bows per 100 mm when admixing in the crimped fibre form. In a method of admixing the electrically conductive fibre which has proved to be particularly effective, the electrically conductive fibres are severed to a length of approximatelyfrom 1/4 to 1/2 of the pile fibre length, are opened by using a opening roller which is known per se and is conventional for parting fibre rovings during rotor spinning, and are conveyed by pneumatic means into the pile fibre flow behind the fibre cutting device.

In a particular embodiment of the invention, the admixture of electrically conducting fibres to the pile fibres is combined with the anti-static finish of the underside of the carpet by a suitable means known per se. It has been shown that thereby, even with such a small portion of electrically conductive fibres as for example, approximately 0.05%, the value of 2000 volts at 30% air humidity which is considered permissible, is not exceeded. The quantity of the admixture of electrically conductive fibres preferably ranges approximately from 0.05 to approximately 2%, wherein, as the titre becomes finer and the fibre length becomes shorter so can their percentage become smaller.Thus, within the scope of the stated limits, as the titre becomes finer and the fibre length becomes shorter, with the part by weight of the elegrically conductive fibres remaining constant, so the grounding of the static electricity is improved and the visibility with the use of light dyes is decreased.

The invention is briefly explained further with reference to the accompanying drawing. A yarn 3 for the pile fibre is conveyed to a fibre severing device 1, 2 by means of a feed device 4 and is cut into staple fibres 5 therein.

Separately from this, a sliver 1 2 consisting completely or partially of electrically conducting fibres is located in a container 1 3. The yarn is then cut in a severing mechanism 11 and then released to form individual fibres by an opening roller 1 0. These are conveyed into the pile fibre flow by a pneumatic transport apparatus 9 via a feed channel 8. They exit there, through nozzle 7, as loose fibres 14 and are mixed with the pile fibres 5 which exit from the fibre severing device 1,2.

The term "electrically conductive fibres" embraces all fibres which are described in the prior art as conducting electricity, for example, metal fibres, particularly steel fibres, pure carbon fibres, fibres produced from a spinnable polymer having an admixture of carbon black or other substances producing a sufficient conductivity of approximately from 25% to approximately 60% and more, dependent on the level of spinnability, but also fibres produced from electrically conductive synthetic fibres.

"Pile fibre" is a term generally known in carpet production and describes the fibre material forming the utilised surface, formed in the backing material by for example tufts.

Claims

1. A method of producing an anti-static carpet fibre by adding a small proportion of electrically conductive fibres to fibres comprising a synthetic linear polymer which form the pile, wherein the pile fibres are first produced from a yarn by means of a fibre severing device and the electrically conductive fibres are formed by severing in a separate working step and are opened to form individual fibres and are mixed in small quantity with the severed pile fibres prior to collection of said severed pile fibres.

2. A method according to claim 1, wherein the quantity of the electrically conductive fibres amount to approximately from 0.05 to 2% by weight.

3. A method according to claim 1 or 2, wherein the titre and the cut length of the electrically conductive fibres are less than the corresponding values for the pile fibres.

4. A method according to any preceding claim, wherein electrically conductive fibres having a titre of approximately from 0.5 to 20 dtex and a length of approximately from 25 mm to 160 mm are mixed with the pile fibres which have a titre of approximately from 2 to 30 dtex and lengths of approximately from 80 to 250 mm.

5. A method according to any preceding claim, wherein electrically conductive fibres having a titre of approximately from 2 to 10 dtex and a length of approximately from 40 to 80 mm are used.

6. A method according to any preceding claim, wherein pile fibres are used which have a titre of approximately from 5 to 20 dtex and a length of approximately from 120 to 200 mm.

7. A method according to any preceding claim, wherein the pile fibre exhibits a crimp of approximately from 60 to 220 bows per 100 mm.

8. A method according to any preceding claim, wherein the electrically conductive fibre is smooth and has a high shrinking capability in the range of at least from 8 to 12%.

9. A method according to any preceding claim, wherein the electrically conductive fibre is crimped and has approximately from 1 5 to 100 crimped bows per 100 mm.

10. A method according to any preceding claim, wherein the electrically conductive fibres are cut from a thin sliver having a sliver weight of approximately from 2 to 10 g per metre, are opened into individual fibres and are fed as such to a pile fibre flow downstream of the pile fibre severing device.

11. A method according to any preceding claim, wherein the electrically conductive fibre is a 100% carbon fibre.

12. A method according to any one of claims 1 to 10, wherein the electrically conductive fibre is a metal fibre.

13. A method according to any one of claims 1 to 10, wherein a steel fibre having a diameter of approximately from 8 to approximately 1 5,um is used as an electrically conductive fibre.

14. A method according to any one of claims 1 to 10, wherein the electrically conductive fibre is produced from a spinnable polymer having an admixture of approximately from 25% to approximately 60%, limited by the spinnability, of a conductive substance in powder form.

1 5. A method according to claim 10, in that the electrically conductive sliver contains electrically conductive fibres in the proportion of approximately 30 to 100% and non-conductive fibres In the proportion of from 0 to apprnxlmately 70%.

1 6. A method according to claim 15, wherein the non-conductive fibre admixture comprises a polyamide.

1 7. A method according to any preceding claim, wherein the electrically conductive fibre, severed to a length of approximately one half to a quarter of the pile fibre length, is opened into individual fibres and conveyed by pneumatic means into a pile fibre flow downstream of the pile fibre severing device.

1 8. A method of producing an antistatic carpet fibre substantially as herein described with reference to the accompanying drawing.

1 9. A method of producing an anti-static carpet product from carpet fibre mixtures produced according to a method claimed in any preceding claim, wherein after forming the pile in the carpet backing, this is provided with an antistatic coating by using a means known per se.

20. An anti-static carpet fibre when produced by a method according to any one of claims 1 to 18.

21. An anti-static carpet fibre, which comprises electrically non-conductive pile fibres and approximately from 0.05 to 2% by weight of electrically conductive fibres, whose individual titre amounts to from 25 to 80% of the electrically non-conductive pile fibre titre and whose length amounts to from 20 to 75% of the pile fibre length.

22. An anti-static carpet fibre, which comprises electrically non-conductive pile fibres and from 0.1 to 1.0% by weight of electrically conducting fibres.